Piston pumps as pressure source for high-pressure applications are well known. Piston pumps may be, for example, single acting reciprocating pumps where a piston draws fluid into a cylinder when stroked in one direction, and pressurizes then expels fluid from the cylinder when stroked in the other direction. Thus, the pump delivers a single pressurized charge of fluid during each stroking cycle. Piston pumps are frequently used in the automobile industry, for example in internal combustion engines, to pump fluids, such as gasoline, engine oil, and transmission fluid at various pressures and speeds.
While piston pumps may be able to generate pressures of 2000 psi and higher, piston pumps typically produce an oscillatory pressure wave originating from the reciprocating piston motion that is characteristic of the piston drive mechanization. Pressure oscillations may create performance noise as well as performance interactions with pressure control devices, such as accumulators or solenoids, downstream of the piston pump. In traditional hydraulic circuit designs, when needed and/or if packaging size allows, accumulators are placed separately in the fluid delivery system to attenuate the pressure peak and valleys of the oscillatory pressure. Typical accumulators are predetermined volumes containing diaphragms, bladders, or bellows, which use the compressibility of gases or elastomers to add compliance, thereby reducing the pressure oscillations produced by the pump piston. The challenge with this traditional approach is the need to find additional packaging space to add accumulators to the hydraulic circuit.
What is needed in the art is a mechanism for attenuating pressure oscillations of a piston pump that does not take up additional packaging space in an assembly.
It is a principal object of the present invention to provide a pressure attenuator that is integrated directly into the piston of a piston pump.
It is a further object of the invention to provide a device and method for compensating pressure spikes directly in the supply pressure chamber.